In multiple chamber electronic manufacturing systems it is desirable to have more than one semiconductor substrate in process at a time. In this way, the electronic manufacturing system is used to obtain maximum throughput. In the art, a robot arm used in an electronic manufacturing system must store one substrate or wafer, fetch and place another substrate, and then fetch and place the stored substrate. Although this improves use of the system and provides improved throughput, the robot arm itself must go through significant repetitive motion—one way to overcome the inefficiency attendant with such wasted motion is to provide a two robot arm system about a common pivot point. Each such robot arm may operate independently of the other, and improved throughput can be obtained through the increased handling capacity of the system, i.e. two arms are better than one.
A Selective Compliant Assembly Robot Arm (also known as a Selective Compliant Articulated Robot Arm) (SCARA) is a multi-axis robot arm that can access any X-Y-Z, or rather R-θ-Z, coordinate within its work envelope. The ‘X’ and ‘Y’ movements are obtained with three parallel-axis rotary joints. The vertical motion ‘Z’ is usually an independent linear axis at the wrist or in the base. SCARA robots are used in assembly operations where the final move to insert the part is a single vertical movement. Component insertion into printed circuit boards may be an example. This is often called “vertical assembly”. Substrate transfer between processing chambers during electronic device manufacturing may be another popular application for SCARA robots.
An attribute of the SCARA is the jointed two-link arm layout, which may be similar to human arms, hence the often-used term, Articulated. This feature may allow the arm to extend into confined areas and then retract or “fold up” out of the way. This is advantageous for transferring substrates from one chamber to another or for loading/unloading process stations that are enclosed.
As larger sized substrates are used in electronic device manufacturing, the equipment (e.g., SCARA robots, processing chambers, transfer chambers, etc.) required for handling and processing the substrates must accommodate the larger substrates. However, the costs associated with simply making the equipment larger can quickly become cost prohibitive, such as the increased cost of manufacturing space, for example. Additionally, as will be further described below, larger equipment may also be undesirable as the larger volume in the processing and robot chambers, for example, may be more difficult keep at a lowest level of vacuum to minimize contamination. Thus, what is needed are systems and methods for handling and processing larger substrates using existing equipment.